Treatment of cellulose esters and ethers



Patented Feb. 1, 1944 2.340.315 TREATMENT or CELLULOSE Es'rsns AND nrncas Charles Hugh Giles and Donald Graham Wilkin- Blackley, Manchester, England, assignors to Imperial Chemical Industries Limited, a

corporation of Great Britain No Drawing. Application September 2, 1941,

Serial No. 409,274. In Great Britain Septemher 2, 1940 3 Claims.

The present invention relates to the treatment of materials, consisting of or containing cellulose esters and ethers, in order to increase the fastness of colourations thereon.

It is known that coloured cellulose esters and ethers are subject to fading on exposure to an atmosphere containing the fumes of burned coal gas. This fading is liable to occur, for instance, when dyed or printed cellulose acetate artificial silk material is stored in a warehouse where coal gas is burned. Thus the material and particularly those portions thereof which are in direct contact with the fume-containing atmosphere, e. g., the edges of piece goods or bundles of yarn suffer change of shade. The consequent disfigurement of the material constitutes a serious disadvantage, for the injuryso occasioned may considerably reduce the value of the material even to the point of its becoming unsaleable.

Such fading due to the action of burned gas fumes may occur on cellulose esters or ethers however dyed, but it is particularly liable to affect dyeings produced by means of anthraquinone derivatives, especially blue or violet dyeings obtained therewith.

We have now found that the aforesaid fading can be considerably reduced or entirely prevented by applying to the dyed material a compound, not being a colouring matter, which is a member of the group comprising benziminazoles and iminazolines (which may also be referred to as 4:5-dihydroglyoxalines) which may carry as substituents alkyl and also, except in the benzene ring, aryl and aralkyl groups but are devoid of hydroxy, amino and nitro groups.

According therefore to the present invention we treat coloured material consisting of cellulose esters and ethers with one or more of the above compounds. As suitable compounds we may use 2-methyliminazoline, 2:4:5-triphenyl-- iminazoline, 2 methylbenziminazole, 2:5 dimethylbenziminazole, l-ethyl z-methylbenziminazole, 2-propylbenziminazole and Z-benzylbenz- 'iminazole, for example.

According to a further feature of the present invention we apply the said compounds to the cellulose esters and ethers at the same time as the latter are being dyed by incorporating the compounds in the dyebath.

Under ordinary storage conditions the fading occasioned by coal gas fumes develops slowly and more or less prolonged storage, depending on the state of the atmosphere and the amount of ob noxious gas present, is necessary before noticeable fading occurs, but fading for testing purposes may be accelerated for instance by exposing to the fumes of burning coal gas in a restricted space. Thus a tinned iron pipe about 6 inches in diameter and five to eight feet high is provided at the bottom end with a ring gas burner and at the top with a framework from which pieces of the material to be tested may be suspended and exposed to the hot ascending products of the burning gas. In a few hours, say six to ten, those dyeings liable to fade under the fumes of burning gas will be noticeably attacked.

If such dyeings prepared in the ordinary way but otherwise untreated are exposed side by side with the same dyeings treated according to the invention, it will be readily seen that the latter show greatly superior resistance to the fading action of the gas fumes.

The invention is not limited to fabrics consisting wholly of cellulose esters or ethers, for example cellulose acetate artificial silk, but is also applicable, for instance, to mixed fabrics of viscose and cellulose acetate artificial silks.

The following examples illustrate but do not limit the invention.

Example 1 A pattern of cellulose acetate artificial silk fabric which has been dyed with 1% by weight of 1:,425z8-tetra aminoanthraquinone is divided into two parts. One part is immersed for one minute in a cold 2% aqueous solution of 2- methyliminazoline, squeezed so as to retain its own weight of liquid and dried. The pattern which has been so treated is then exposed together with the untreated pattern to the fumes from burning coal gas in an apparatus such as that already described above for 10 hours.

At the conclusion of the test the untreated pattern is considerably faded, the shade having become much duller than the original, whereas the treated pattern has faded only to a slight degree.

Example 2 1 part of 1:4z5:B-tetraaminoanthraquinone, 2 parts of Z-methylbenziminazole and 9 parts of 50% Turkey red oil are dissolved in 3000 parts of water. This constitutes the dyebath.

100 part of cellulose acetate artificial silk fabric are immersed in the dyebath and the temperature thereof raised during 15 minutes to C. and kept thereat for %-hour. The material is then removed, well rinsed and dried. It is found to have greatly improved resistance to 2 2,840,375 I g g a v burned gas fumes compared with material which 1. Process for reducing the fume-fading or" has been dyed in a similar manner but omitting dyeings on textile materials comprising essentialthe z-methylbenziminazole. 1y cellulose acetate which comprises treating said Example 3 materials with 2-methyl-benziminazole.

5 2. The process according to claim 1 wherein A pattern of cellulose acetate artificial silk the 2-niethyl-benziininazole is added to the dye i'abric dyed with 1% by Weight 01 t ifii bath with which said material is dyed. aminoanthraquinone is immersed in a cold 1% 3. Dyedtextile materials comprising cellulose ethyl 10 o uti n of 2i5-dlmethylbenzimlmlacetate which materials have been treated with 2- zole. The pattern is squeezed nd i on w methylbenziminazole, and which material; are xp su o gas fumes as described above. it is further characterized by resistance to fume-tadiound to be only slightly changed in shade, m whereas untreated material is badly discoloured. 7 CHARLES HUGH GILES.

We claim: DONALD GRAHAM WILKINSON. 

